Optical storage discs have become available for more than 15 years. Majority of users request for the right to reasonably copy optical storage discs, and many countries have established laws on protection of general users' right to the use of optical storage discs within a legally permitted scope. However, the so-called “reasonably copy” also causes the problem of “illegal reproduction” and hence serious loss to copyrighters.
In the past ten years, many copy protection techniques had been developed and announced. Majority of the existing copy protection techniques involve damaging of the optical disc surface; including logical damage developed based on the optical disc specification or physical damage produced during the optical disc manufacturing process. Recently, quite a few special copy software programs have become available. They utilize the reset time of the optical disc drive or check the actual time used to read the optical disc to circumvent the logical damage or the physical damage formed on the optical disc. As a result, either the logical or the physical damage on the optical disc surface fails to effectively prevent the optical disc from being illegally copied without authorization.
Optical discs utilizing the hybrid copy protection technique that combines encryption, logical damage and physical damage can be now arbitrarily copied simply using some copy software. Even though the decoding software and the reverse engineering of software are clearly prohibited by the existing copyright law, it is still very difficult to completely stop users from copying optical discs without authorization.
Even for some mega-manufacturers, who use non standard optical disc burning software and at the same time manufacture non standard optical disc drives for reading a “unique mark” on the optical discs, also encounter with the threat of decoding of software or reverse engineering of software in the forms of firmware or plug-in; and their copy protection means are cracked by the firmware or plug-in. This is not because the unique mark is a wrong idea but because the unique mark can only be read out by the non standard optical disc drive. A cracker can easily crack the copy protection by circumventing the reading of the unique mark.
However, in this event every optical disc is provided with a really unique mark that must be read accurately for decoding accurately, it would then be very difficult for the crackers to crack the copy protection by using some plums in or by circumventing the reading of the unique mark. Only in this way, it is possible to overwhelmingly suppress reproduction without authorization.
Currently, all the commercially available copy software or advanced optical disc drives are able to quickly detect various copy protection means equipped on the optical discs. In the past, a physical damage (bad sectors) was utilized as a copy protection means for optical discs, Nowadays, since the newest optical disc drives can be reset at a very quick speed, such physical damage cannot stop the reading of the advanced optical disc drives. Contents of the original data can still be read out from among bad sectors. In view of these adverse conditions, it is necessary to develop an innovative copy protection technique for optical storage devices so as to eliminate the serious problem of reproduction without authorization.